| 近60 a来中国西南春季持续性干旱异常特征分析 |
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| 引用本文： | 杨金虎,张强,王劲松,尚军林,张海耀.近60 a来中国西南春季持续性干旱异常特征分析[J].干旱区地理,2015,38(2):215-222. |
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| 作者姓名： | 杨金虎 张强 王劲松 尚军林 张海耀 |
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| 作者单位： | （1 中国气象局兰州干旱气象研究所 甘肃省干旱气候变化与减灾重点实验室 中国气象局干旱气候变化与减灾重点开放实验室，甘肃 兰州 730020； 2 甘肃省定西市气象局， 甘肃 定西 743000） |
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| 基金项目： | 国家重点基础研究发展计划项目2013CB430206、公益性行业（气象）科研专项GYHY201306027共同资助 |
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| 摘 要： | 利用1953-2012年中国西南地区44个气象台站的逐日降水、温度以及NCAR/NCEP月平均高度场、风场、地面气压、比湿、垂直速度和NOAA月平均海表温度资料，分析了西南地区4～5月持续性干旱的大气环流特征，并对前期印度洋海表温度对西南地区4～5月持续性干旱的影响进行了初步探讨，结果表明：在西南4～5月持续性干旱年，同期4、5月乌拉尔山脊偏弱，东亚大槽南段偏弱，南支槽也偏弱，中高纬西风带偏强，这样北方冷空气和西南暖湿气流均偏弱；对应西南地区表现为异常的下沉运动，同时水汽输送通量表现为异常的辐散中心，从而使得西南地区发生干旱。另外，在西南4～5月持续性干旱年，从前期2月中印度洋异常偏暖的海表温度区逐渐向东移动，在4～5月到达东印度洋，东印度洋异常偏暖的海表温度加热该地区的大气，使得该地区表现出异常的上升运动，导致哈德莱环流增强，而我国西南地区对应异常的下沉气流，从而使得西南地4～5月发生干旱。
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| 关 键 词： | 中国西南 春季 持续干旱 大气环流 海温 |
| 收稿时间： | 2014-03-18 |
Spring persistent droughts anomaly characteristics of over the southwest China in recent 60 years |
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| YANG Jin-hu,ZHANG Qiang,WANG Jin-song,SHANG Jun-lin,ZHANG Hai-yue.Spring persistent droughts anomaly characteristics of over the southwest China in recent 60 years[J].Arid Land Geography,2015,38(2):215-222. |
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| Authors: | YANG Jin-hu ZHANG Qiang WANG Jin-song SHANG Jun-lin ZHANG Hai-yue |
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| Institution: | （ 1 Lanzhou Institute of Arid Meteorology of China Meteorological Administration Key Laboratory of Arid Climate Change and Reducing Disaster of Gansu Province Key Laboratory of Arid Climate Change and Disaster Reduction of China Meteorological Administration，Lanzhou 730020，Gansu，China ；2 Dingxi Meteorological Bureau of Gansu Province，Dingxi 743000，Gansu，China） |
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| Abstract: | With 44 stations temperature and precipitation data of day by day in Southwest China，NCAR / NCEP monthly mean height field，wind，surface pressure，specific humidity，vertical speed，and NOAA monthly mean sea surface temperature data，the potential evaporation was calculated by Thornthwaite method. Through analyzing monthly precipitation and potential evaporation percentage proportion spring precipitation from March to May.and taking into account the precipitation and potential evaporation of April and May accounted for the major part of the spring，we selected the period of April and May as our research subject and by using homogenization drought index of precipitation and potential evaporation，the persistent drought of spring was defined at first in Southwest China，and then the abnormal years of the persistent drought were determined. By Synthetic analysis method，the atmospheric circulation features of persistent drought over Southwest China from April to May was analyzed. Influence prophase sea surface temperature of Indian Ocean region on persistent drought over the southwest China from April to May was discussed，The results showed that: in the persistent drought years from April to May over Southwest China，Ural ridge was weak clearly，the southern section of East Asian trough and south branch trough leaned weak over the same period from April to May，but leaned strong westerly in middle and high latitudes，thus the northern cold air of Southwest China's influence leaned weak，and the southwest warm and wet air transported to southwest China was also weak. Correspondence vertical movement showed the abnormal downward motion over Southwest China,,at the same time the moisture transport flux showed abnormal divergence center，the circumfluence led to drought in the Southwest China. and this circulation features had good continuity from April to May，So persistent droughts occurred over Southwest China in spring. In addition，from the beginning of February in the Indian Ocean sea，we observed that the surface temperature display changed. In persistent drought years from April to May over Southwest China，the warmer sea surface temperature anomaly area was gradually moving eastward from the previous February in the Indian Ocean and reached to the Eastern Indian Ocean in April-May，and the anomaly warmer sea surface temperature heated the atmospheric in Eastern Indian Ocean，leading to an abnormal upward motion over Eastern Indian Ocean and Hadley circulation enhancement，But the abnormal downward motion over Southwest China eventually led to drought phenomenon occurred from April to May in Southwest China. This might be the primary mechanism Pre-Indian Ocean sea surface temperature which influenced the spring persistent drought of Southwest China. Of course，cause of persistent droughts over Southwest China is complicated，for example，Pacific sea surface temperature also affected the persistent droughts over Southwest China,for the water vapor source of Southwest China comes part from the Indian Ocean，part from the Pacific. But what’s the main factors needs further study and analysis. However，the research provides some references for short-term climate projections of spring persistent drought phenomena over the Southwest China. |
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| Keywords: | southwest China spring persistent drought atmospheric circulation SST |
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